What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Such flat gaskets typically include passage openings for fluids through which fluid can flow from one side of the flat gasket to the other side of the flat gasket. In addition, functional elements may be inserted into such passage openings, eg valve elements blocking passage in one direction, or orifice elements defining passage in one or both directions.
In the existing industrial technology field, screws are mostly used for the connection between components. For many electronic products, because the products are more and more thin and light, the connection between the shell and the shell is often affected by the thickness of the shell. , usually need to use screw column structure for connection. Take the existing outdoor three-proof mobile phone as an example: the screw column structure includes a shell, a shell and a screw, the shell is provided with a plurality of screw columns, and the nuts in the screw columns are injected through the in-mold injection process. Directly integrated with the housing. Due to the special use environment and use requirements of outdoor three-proof mobile phones, they need to have good high-strength anti-drop performance, while the three-proof mobile phones in the prior art are subjected to high-strength drop tests due to the fundamental stress concentration of the screw column. During the process, problems such as cracking of the screw column or breaking from the root occur.
In view of the deficiencies of the prior art, a simple structure is provided, which can ensure that the nut body and the washer are assembled together during the production of the wheel nut, and will not be separated from each other in any occasion, so as to ensure the reliability of the assembly, and the nut will no longer appear. The wheel nut assembly that needs to be reassembled after use or placement saves time and effectively improves the convenience of the wheel nut when it is used or placed
1. For low strength (below 500 N/mm2 or below 60000 psi) bolts use general soft steel, generally use SAE 1008 or JIS SWRM 8 (or SWRCH 8). 2. Lower strength (600 N/mm2 or 74000 psi) ) bolts use general soft steel, but limited carbon content grade, generally use SAE 1010 - 1015 or JIS SWRM 10 - 15 (or SWRCH 10 - 15). .3. Higher strength ( 800 N/mm2 or 125000 psi ) bolts of medium carbon steel, low carbon boron steel plus quenching and tempering, generally use SAE 1035 - 1040 or SWRCH 35K - 40K. 4. High strength (900 N/mm2 or more or 150000 psi or more) bolts use medium carbon Alloy steel or low carbon boron steel, in terms of application, if the metric Class 10.9 uses low carbon boron steel, the imprint should be added under the series imprint to become 10.9, and the imprint of the inch 8.2 grade is also used with the general Grade 8 bolts The imprint is different for easy identification. High-strength bolts made of low carbon boron steel cannot be used in high temperature conditions. The design strength exceeds Class 12.9 or ASTM A574 ultra-high strength bolts are limited to medium carbon alloy steel plus quenching and tempering. The performance grades of bolts for steel structure connection are divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc. Among them, the bolts of grade 8.8 and above are made of low-carbon alloy steel or medium-carbon steel and are heat-treated (quenching, tempering), commonly known as high-strength bolts, the rest are commonly known as ordinary bolts. The bolt performance grade label consists of two parts of numbers, which represent the nominal tensile strength value and yield ratio of the bolt material respectively. For example, a bolt with a performance level of 4.6 means: 1. The nominal tensile strength of the bolt material is 400MPa; 2. The yield ratio of the bolt material is 0.6; 3. The nominal yield strength of the bolt material is 400×0.6=240Mpa . Performance level 10.9 high-strength bolts, after heat treatment, can achieve: 1. The nominal tensile strength of the bolt material is 1000MPa; 2. The yield ratio of the bolt material is 0.9; High-strength bolts, processing and manufacturing problems are compared Small, general fastener manufacturing companies can master the manufacturing process; but problems are prone to occur in material selection and heat treatment. Material selection is the primary link. Various alloying elements have a great influence on the properties of the material, and the material must be subjected to spectral composition analysis; secondly, the fracture problem and the choice of heat treatment process have a great influence and are very important. Dealers and traders must control the inspection and performance testing links; automotive fasteners have high requirements and must carefully control the quality.
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